The present invention relates to a composition for preparing substances having nano-pores. More specifically, the present invention relates to a composition comprising cyclodextrin derivatives as porogen, so as to form uniform nano-pores with a diameter less than 50 xc3x85.
Substances having nano-pores have been known to be useful for absorbents, carriers for catalysts, thermal insulators and electric insulators in various fields. In particular, they have been recently reported useful as materials for insulating films between interconnect layers in microelectronic devices. Feature size in the microelectronic device has to be reduced because circuit density in multilevel integrated circuit devices is increasing. But, there are problems such as R(resistance)xc3x97C(capacitance) delay due to crosstalk between interconnect lines. Therefore, dielectric constant of the interlayer insulating film should be lowered so as to decrease RC delay as much as possible. For this purpose, there have been attempts to use materials with low dielectric constant in the insulating film. For example, U.S. Pat. Nos. 3,615,272, 4,399,266 and 4,999,397 disclose polysilsesquioxanes with a dielectric constant of 2.5xcx9c3.1 which can be used in Spin On Deposition (SOD), as an alternative for SiO2 with a dielectric constant of 4.0 which has been used in Chemical Vapor Deposition(CVD). In addition, U.S. Pat. No. 5,965,679 describes organic high molecules with a dielectric constant of 2.65xcx9c2.70, polyphenylenes. However, the dielectric constants of the previous matrix materials are not sufficiently low to achieve a very low dielectric constant less than 2.50 required for high-speed devices.
To solve this problem, there have been various trials to incorporate air bubbles into these organic and inorganic matrixes at a nano-scale. In this connection, U.S. Pat. No. 6,114,458 describes the use of lactone-based dendrimeric high molecules as porogen, which are degradable in the heating step to form a thin film. Further, U.S. Pat. Nos. 6,107,357 and 6,093,636 disclose a method for preparing low dielectric constant(k less than 3.0) substances comprising the steps of: mixing the lactone-based dendrimers or vinyl-based high molecular dendrimers such as polystyrene, polymethacrylate, polyester and the like along with the conventional organic or inorganic matrix; coating a thin film by using the mixture; and decomposing the porogens contained in the mixture at a high temperature to form nano-pores.
However, the porous substances produced by such methods have a problem that their pore sizes are as large as 50xcx9c100 xc3x85 in diameter and distribution thereof is inhomogeneous.
A feature of the present invention is a novel porogen for preparing substances wherein a number of nano-pores with a diameter less than 50 xc3x85 are uniformly distributed.
Another feature of the present invention is a composition for preparing substances wherein a number of nano-pores with a diameter less than 50 xc3x85 are uniformly distributed.
Still another feature of the present invention is a method for forming insulating film between interconnect layers in microelectronic devices, which have a dielectric constant kxe2x89xa62.5, by using said composition.
In accordance with one aspect of the present invention, there is provided a composition for preparing substances having nano-pores, said composition comprising a cyclodextrin-based derivative, a thermo-stable organic or inorganic matrix precursor, and a solvent being capable of dissolving said two solid components.
In accordance with another aspect of the present invention, there is provided a method for forming interlayer insulating film between interconnect layers in microelectronic devices, said method comprising coating a substrate with said composition through spin-coating, dip-coating, spray-coating, flow-coating or screen printing; evaporating the solvent from said substrate; and heating said substrate at 150xcx9c600xc2x0 C. under inert gas atmosphere or vacuum condition.
In accordance with still another aspect of the present invention, there is provided the substances having nano-pores produced by the use of said composition, and their use as heat resisting materials, electric insulators, absorbents, carriers for catalysts, and so on.